Medical workers have discovered that certain dyes not only selectively stain neoplastic or tumorous tissue but also fluoresce in response to irradiation and are photodynamically cytotoxic in response to a proper wavelength of light in the presence of oxygen within living tissue. One of the dyes that is presently preferred for these characteristics contains hematoporphyrin or hematoporphyrin derivatives that when administered intravenously remain at higher concentrations for longer periods of time in traumatized or malignant tumorous tissue than in normal tissue. This dye also has a strong absorption peak centered at a wavelength of approximately 407 nanometers and responds to excitation at about this wavelength by fluorescing at a wavelength of about 614 nanometers. This makes tumor diagnosis possible by injecting the dye, allowing it to concentrate in tumorous tissue, irradiating the tissue with deep blue violet light, and observing red fluorescence. This same dye has a photodynamic absorption peak at a wavelength of about 631 nanometers and is cytotoxic to malignant tissue containing the dye when irradiated with red light of about this wavelength.
For diagnostic purposes, present workers have been using the krypton ion laser for its 406.7/413.1 nanometer lines matching the 407 nanometer absorption peak of hematoporphyrin. For treatment purposes, they have used several light sources including a xenon arc lamp filtered to transmit only red light, a Helium-Neon laser operating at 632.8 nanometers, and an argon ion laser-pumped Rhodamine-B dye laser tuned to about 631 nanometers.
My invention recognizes the problems involved in this art and suggests a way that a single laser can simultaneously provide both frequencies required for diagnosis and treatment. I also suggest practical ways of transmitting the light to the tissue and more convenient and economical equipment for medically practicing photoradiation diagnosis and treatment.